A system-on-chip (SoC) is an integrated circuit that combines different components, such as those traditionally associated with a processor-based system, into a single chip or, in some applications, within a small number of interconnected chips. The SoC may include advanced processors, various homogeneous and/or heterogeneous processing agents, and additional components such as networking devices, e.g., routers, controllers, bridge devices, memories, and so forth.
One implementation of a SoC may include an integrated on-chip system fabric (IOSF) specification issued by a semiconductor manufacturer to provide a standardized on-die interconnect protocol for attaching intellectual property (IP) blocks of varying types within the SoC. The IP blocks may include general-purpose processors, such as in-order or out-of-order cores, fixed function units, graphics processors, and controllers.
By standardizing an interconnect protocol such as IOSF, a framework is thus realized for a broad use of IP agents in different types of chips. The standardized interconnect protocol enables the semiconductor manufacturer to efficiently design different types of chips across a wide variety of customer segments. Further, the standardized protocol specification enables third parties to design logic, such as IP agents, to be incorporated into such chips. By providing multiple options for many facets of the interconnect protocol, reuse of designs is efficiently accommodated.
Primary scalable fabric (PSF) is a highly configurable SoC backbone IP based on the IOSF standard. PSFs are used to create an IOSF-compliant hierarchy that provides interconnection of IP blocks within the SoC or within an I/O subsystem. A single SoC may have one or more PSFs, at least one of which is coupled to the central processing unit (CPU) through a system agent (SA).
Under PSF 1.0, all transactions pass through the SA to the CPU. Debugging operations are thus performed at the SA, and all agents of the SoC are potential targets for the debug.
By contrast, PSF 2.0 supports peer-to-peer transactions between agents, which essentially removes the SA from the transaction path. This complicates the ability of a debugger to reach all entities on the SoC. (The IOSF specification, as well as PSF 1.0 and 2.0, are developed by Intel Corporation of Santa Clara, Calif.)
Thus, there is a need for a debug solution for an integrated on-chip system fabric supporting peer-to-peer transactions.